The Internet Protocol (IP for short, Internet Protocol) multicast technology implements point-to-multipoint data transmission efficiently. The multicast technology saves bandwidth efficiently, controls network traffic, relieves the load of a server, and reduces network load. Therefore, the multicast technology is applied in real-time transmission of a video service, multimedia conference, game, emulation, and so on.
The modern network service imposes higher and higher requirements on the real-time feature. For example, the services such as voice over Internet Protocol (VoIP for short, Voice over Internet Protocol), online game, and online video are very sensitive to packet loss. In the running process of the IP multicast, if a network is faulty, a unicast routing protocol needs to perform calculation first according to the change of the network topology to implement convergence, and then a multicast routing protocol such as Protocol Independent Multicast (PIM for short, Protocol Independent Multicast) Protocol reselects an inverse path (RPF for short, Reverse Path Forwarding) to forward the packet to an upstream node according to a new unicast route, and sends a request to an upstream router hop by hop, and the transmission of the multicast traffic is not recovered until a new multicast forwarding path is created. Therefore, before the new multicast forwarding path is created successfully, the multicast traffic is not transmitted normally, which leads to service interruption. Persons skilled in the art are exploring how to prevent interruption of multicast traffic transmission when the network is faulty, but no effective technical solution to such a problem has been worked out.